1. Field of the Invention
The present invention relates in general to a high-temperature gas blower impeller, a gas blower device equipped with such impeller, and a high-temperature gas circulating furnace equipped with such gas blower device, and more particularly to a technique relating to improvements in the material of vanes or blades of the impeller.
2. Discussion of the Related Art
An blower or fan is used to blow a gas of a relatively high temperature in various industrial furnaces such as heat treating and heating furnaces. Such a high-temperature blower is utilized, for example, to stir or circulate a high-temperature atmosphere or gas of around 800.degree. C. within a furnace. Since the blower is used in such severe thermal environment, a rotating impeller of the blower is usually made of a heat-resistant steel capable of withstanding a reaction force and a centrifugal force which are produced during an operation of the blower to circulate the atmosphere.
However, the upper limit of the operating temperature of the impeller made of a heat-resistant steel is about 850.degree. C., above which the impeller does not have a sufficient strength. Also, the strength of the impeller limits the operating speed of the impeller to 1000 r.p.m. or so. To obtain a desired capacity or gas quantity, therefore, the gas blower device must be relatively large-sized. Whereas, it is desired to minimize the size of the gas blower device, particularly where the device is built in a furnace, such as a gas circulating furnace adapted to circulate a high-temperature gas within a heating chamber. In this case, an increase in the size of the blower device will undesirably lead to an accordingly large size of the furnace body.